Cover title

"For the Montana Natural Heritage Program, Bureau of Land Management - Billings Resource Area, Custer National Forest."

"May 1, 1990."

Includes bibliographical references (leaves 19-20)

"U9OWOR01MTUS."

This report documents the results of a study of bat occurrence in the Pryor Mountains of south central Montana. The field research was conducted from 15 June to 10 September, 1989. Bats were captured in mist nets set over ponds, streams, and springs and at the entrance of two caves. Numbers of bats captured were greatest at Little Ice Cave and at Mystery Cave. Capture success was considerably lower at water sources, but a greater diversity of species were captured at these sites, particularly at Sage Creek campground and Gyp Spring. Most of the species captured occurred throughout the area, with the exception of the pallid bat, Antrozous pallidus, and the silver-haired bat, Lasionycteris noctivagans, which were more restricted in distribution. Eight individuals of Antrozous pallidus were captured at Gyp Spring. This species was known previously in Montana from only one specimen taken at Gyp spring (Shryer and Flath, 1980). Of the eight individual pallid bats netted in 1989, four were lactating females, indicating that this species breeds in Montana. Several of the species of bats found in the Pryor Mountains were captured in numbers significantly different from an expected 1:1 sex ration. This was especially true at Mystery Cave and Little Ice Cave, suggesting that in some species, male and females may be differentially utilizing habitat. Bat activity at both Mystery Cave and Little Ice Cave indicated that these caves provide important summer roosting habitat for bats. Additionally, both caves possess characteristics which may make them important as hibernacula

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